A hydrogen sulfate enriched salt water layer (probably formed from decaying organics) at about 90′ within a cenote in Mexico has produced a surreal underwater river landscape.  The video gets very interesting after the 3:15 minute mark.

Be sure to check out the still pictures by Anatoly Beloshchin at the following link …

http://www.123inspiration.com/cenote-angelita-a-hidden-underwater-river-in-mexico/